Zhang Zhou, Li Ping, Sun Ping
Translational Medical Centre, Wuxi No. 2 People's Hospital, Affiliated Wuxi Clinical College of Nantong University, Wuxi, Jiangsu 214002, P.R. China.
Translational Medical Centre, Wuxi No. 2 People's Hospital, Affiliated Wuxi No. 2 People's Hospital of Nanjing Medical University, Wuxi, Jiangsu 214002, P.R. China.
Oncol Lett. 2022 Jul 8;24(3):303. doi: 10.3892/ol.2022.13423. eCollection 2022 Sep.
The expression of sterile α motif and histidine/aspartic acid domain-containing protein 1 (SAMHD1) and its mutation play a key role in the prognosis of colon cancer. The aim of the present study was to investigate the mechanism and the role of SAMHD1 in colon cancer. Microarray data from 187 patients with colon cancer and 45 adjacent normal tissue obtained from the Gene Expression Omnibus (GEO) were analyzed. A protein-protein interaction (PPI) network was constructed to identify key genes associated with colon cancer prognosis. Cox proportional hazard regression and survival analyses were performed to identify the potential for SAMHD1 to serve as a prognostic biomarker. Immunohistochemistry (IHC) and immunofluorescence (IF) were performed to assess the expression levels and distribution of SAMHD1 in tissues and cells. Western blotting (WB) and Cell Counting Kit-8 (CCK-8) assays were used to identify the proliferation and apoptotic effects of SAMHD1 on HT-29 (Cas9-SAMHD1) cell lines. A total of 6,905 consistently differentially expressed genes were identified in the GEO database. Through the PPI network, SAMHD1 was found to be associated with Kirsten rat sarcoma virus (KRAS). SAMHD1 expression was negatively associated with KRAS. Proportional hazards regression and survival analyses demonstrated that low expression of SAMHD1 was associated with increased patient mortality. IHC and IF results demonstrated that SAMHD1 expression in patients with colon cancer was decreased compared with controls (both P<0.05). CCK-8 and WB results showed that proliferation was significantly promoted, and the expression levels of apoptosis-related proteins were significantly inhibited in the D137N and D311A groups as a result of a mutation in the deoxynucleoside triphosphohydrolase (dNTPase) site (both P<0.05 vs. wild-type). Proliferation was inhibited and apoptosis-related protein expression levels were promoted in the wild-type (WT) and D137N groups following 20 µg/ml 5-fluorouracil (5-FU) treatment (both P<0.05). WB and CCK-8 results showed cell proliferation was promoted and cell apoptosis-related protein expression was inhibited in the D137N group following treatment with 20 µg/ml 5-FU (all P<0.05) compared with the WT group. In conclusion, SAMHD1 expression was low in colon cancer. The dNTPase function of SAMHD1 may inhibit colon cancer cell proliferation and may enhance apoptosis. In addition, first-line chemotherapy with 5-FU has a time-dependent effect, which may provide novel options for clinical treatment of colon cancer.
含无菌α基序和组氨酸/天冬氨酸结构域蛋白1（SAMHD1）的表达及其突变在结肠癌预后中起关键作用。本研究旨在探讨SAMHD1在结肠癌中的作用机制。分析了从基因表达综合数据库（GEO）获得的187例结肠癌患者和45例相邻正常组织的微阵列数据。构建蛋白质-蛋白质相互作用（PPI）网络以鉴定与结肠癌预后相关的关键基因。进行Cox比例风险回归和生存分析以确定SAMHD1作为预后生物标志物的可能性。采用免疫组织化学（IHC）和免疫荧光（IF）评估SAMHD1在组织和细胞中的表达水平及分布。使用蛋白质印迹法（WB）和细胞计数试剂盒-8（CCK-8）检测来鉴定SAMHD1对HT-29（Cas9-SAMHD1）细胞系的增殖和凋亡作用。在GEO数据库中总共鉴定出6905个持续差异表达基因。通过PPI网络发现SAMHD1与 Kirsten大鼠肉瘤病毒（KRAS）相关。SAMHD1表达与KRAS呈负相关。比例风险回归和生存分析表明，SAMHD1低表达与患者死亡率增加相关。IHC和IF结果表明，与对照组相比，结肠癌患者中SAMHD1表达降低（均P<0.05）。CCK-8和WB结果显示，由于脱氧核苷三磷酸水解酶（dNTPase）位点突变，D137N和D311A组的增殖显著促进，凋亡相关蛋白表达水平显著抑制（与野生型相比均P<0.05）。在20μg/ml 5-氟尿嘧啶（5-FU）处理后，野生型（WT）和D137N组的增殖受到抑制，凋亡相关蛋白表达水平升高（均P<0.05）。WB和CCK-8结果显示，与WT组相比，20μg/ml 5-FU处理后D137N组的细胞增殖促进，细胞凋亡相关蛋白表达受到抑制（均P<0.05）。总之，结肠癌中SAMHD1表达较低。SAMHD1的dNTPase功能可能抑制结肠癌细胞增殖并可能增强凋亡。此外，5-FU一线化疗具有时间依赖性效应，这可能为结肠癌的临床治疗提供新的选择。
